The infrared (IR) optical spectrum contains vibrational and rotational resonances of many molecules. Using the IR spectral range to probe material may allow a set of unique molecular fingerprints to be obtained. Molecules may have absorption lines in the IR spectrum due to their vibrational and rotational levels. Accordingly, IR optical spectroscopy is a powerful tool for many applications including material analysis, environmental sensing, health diagnostics and others. FIG. 1A is a plot 100a of money (in million of dollars or million $) as a function of year showing the change in values of infrared spectroscopy for different applications in 2009 and 2014. FIG. 1B is a pie chart 100b showing the market share of different vendors of Fourier Transform—Infrared (FTIR) and Fourier Transform—Near Infrared (FT-NIR) in 2011.
Visible-near infrared (VIS-NIR) range optical spectrometers and refractometers may face challenges when they are applied in the IR range, such as inferior performance (in terms of noise level and efficiency) and/or high cost of IR components such as IR optics, IR light sources and IR detectors. Direct Transmission (DT) spectroscopy is now obsolete, while Fourier Transform Infrared (FTIR) is well-established but faces many of the abovementioned problems.
A low-end bench-top Fourier Transform Infrared (FTIR) spectrometer, which is a commonly used and commercially available system applicable for use in a broad spectral range (200 cm−1-7000 cm−1) and with high resolution (˜4 cm−1), may cost $20,000.